tnick, go for it. Years ago, one of my cousins had a small ceremony for close family and friends, then a huge reception later on. If anyone was upset or offended, I sure did not see it! The invitations were sent out as a reception invite - they inserted cards into the invites for the ceremony.
As a side note: Certain religions do not allow "non-members" to attend the wedding ceremonies, such as Mormons who have a wedding in a LDS church. I have been invited to many a reception by a mormon couple, and have never been offended by it.
Enjoy your wedding and your party!